Field of the Invention
The invention relates to an accessory gearbox for controlling at least one wing flap of an aircraft, in particular of a helicopter.
Description of the Related Art
As shown in FIGS. 1 and 2, an aircraft such as a helicopter comprises, in a known manner, a front-access (or frontal) engine comprising a gearbox 40 for peripheral equipment 50 of said engine, referred to as the accessory gearbox 40. Here and in the following, the term “front” means the side from which the accessory gearbox 40 is accessed for carrying out maintenance thereof. In the same way, the term “rear” means the side opposite the front side with respect to the accessory gearbox 40.
As shown in FIG. 1, an accessory gearbox 40 of this kind comprises, in a known manner, a wing flap control rod 15 extending in part inside a conduit 45 of the gearbox 40 so as to slide inside said conduit when it is driven in translation.
It is known to mount an actuator 20 for driving said control rod 15 on the front face of the casing 42 of such a gearbox 40 by means of fixing arms (not shown).
The actuator 20 comprises a hollow body 21 inside which a piston 23 slides, said piston being mounted on a piston rod 22, referred to as a power rod, extending in part outside the body. The control rod 15 is connected at one end to the wing flaps to be controlled and, at the other end, end-to-end with the free end of the piston rod 22 outside the body. The piston rod 22 and the control rod 15 are connected by means of a connection shaft 30 perpendicularly crossing the control rod 15 and the piston rod 22 and fixing them together for conjoint translational movement. Thus, progressing from the front to the rear, there is firstly the body of the actuator 20, then the portion of the piston rod 22 which extends outside the body, and finally the wing flap control rod 15, as shown in FIG. 2. When the actuator 20 is actuated, the circulation of fluids on either side of the piston 23 causes said piston to move in one direction or the other such that the piston rod 22 in turn drives in translation the wing flap control rod 15.
When the engine is undergoing maintenance, it is necessary to mount (or demount) the connection shaft 30 between the piston rod 22 and the control rod 15. However, as shown in FIG. 1, this connection shaft 30 cannot be accessed directly from the front by an operator as it is located behind the actuator 20 in a region C located between the body of the actuator 20 and the accessory gearbox 40. An assembly of this kind therefore requires at least part of the peripheral equipment 50 of the gearbox 40 to be demounted in order to gain lateral access to the connection shaft 30, thereby leading to wasted time and increasing the aircraft maintenance costs, and thus has a first drawback.
Moreover, despite demounting the peripheral equipment 50 of the gearbox 40 in this way, the connection shaft 30 remains difficult to access and the handling of the shaft 30 for mounting (or demounting) is carried out blind by the operator, making it more complex and time-consuming, which is a second drawback.
Furthermore, as shown in FIG. 1, arranging a region C providing access to the connection shaft 30 between the accessory gearbox 40 and the actuator 20 requires the actuator 20 to be moved away from the accessory gearbox 40 towards the front. Such a relocation requires the actuator 20 to be mounted on the accessory gearbox 40 with a significant overhang, which makes the actuator 20 particularly vulnerable to the various vibratory movements of the turboshaft engine, resulting in problems with the mechanical strength of the fixings of the actuator 20 to the casing 42 of the accessory gearbox 40, which is a third drawback.
Finally, a portion of the external fluid inlet and outlet ducts 27A and 27B of the actuator 20, shown in part in FIG. 1, may prevent access to the access region C, thereby further complicating maintenance operations, which is a fourth drawback.